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EMBO J. 1993 Aug;12(8):3249-59.

Chromatin disruption in the promoter of human immunodeficiency virus type 1 during transcriptional activation.

Author information

1
Laboratory of Viral and Molecular Pathogenesis, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892.

Erratum in

  • EMBO J 1993 Dec;12(12):4900.

Abstract

Chromatin organization of eukaryotic promoters is increasingly recognized as an important factor in the regulation of transcription in vivo. To determine the role of chromatin in HIV-1 expression, we have examined the nucleosome organization of the promoter of HIV-1 under low and high transcription rates. Independently of the cell line examined, nucleosomes are precisely positioned in the viral 5' long terminal repeat (5' LTR) and define two large nucleosome-free regions encompassing nt 200-450 and 610-720. A nucleosome positioned between these two regions, immediately after the transcription initiation site (nuc-1), is disrupted following TPA or TNF-alpha treatment. The disruption of nuc-1 from DNA is independent of DNA replication since it is completed in 20 min and independent of transcription as it is alpha-amanitin insensitive. A model is proposed in which nuc-1 plays an organizing role in the HIV-1 promoter to bring in close proximity factors bound to DNA in the two nucleosome-free regions, upstream and downstream of the site of transcription initiation. These results define chromatin as an integral component of the HIV-1 transcriptional regulatory machinery and identify a chromatin transition associated with activation of viral gene expression.

PMID:
8344262
PMCID:
PMC413592
[Indexed for MEDLINE]
Free PMC Article

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